Determination and monitoring of laser energy

ABSTRACT

The invention relates to an apparatus and a method for determining the energy of a laser. In particular, the invention relates to an initial determination of a laser energy and the monitoring of the laser energy preferably of an excimer laser for use in a refractive laser system for treatment of any eye. An apparatus for determining an energy of an excimer laser comprises a tool comprising an area being ablated with a plurality of laser pulses of said excimer laser using at least one predetermined multi spot ablation pattern, said ablation area comprising a specific ablation area being as large as the ablation area or smaller, an image capturing means for capturing at least one image comprising at least said specific ablation area of the tool; an analyzing means for analyzing said at least one image, wherein the size of the specific ablation area provides a measure of the energy of the excimer laser.

FIELD OF INVENTION

The invention relates to an apparatus and a method for determining theenergy of a laser. In particular, the invention relates to an initialdetermination of a laser energy and the monitoring of the laser energypreferably of an excimer laser for use in a refractive laser system fortreatment of any eye.

BACKGROUND OF THE INVENTION

For the initial determination of a laser energy of a refractive lasersystems usually a disposable energy calibration tool is used. Thiscalibration tool consists of a glued foil on top of a coloured baseplate. A laser system with nominal fluence level (expressed in mJ/cm²)will penetrate the foil with a specified number of pulses having twotarget positions on the tool. To test a laser system the number of laserpulses necessary to penetrate the foil is counted and the userdetermines when the foil is ablated, i.e., the coloured base plate isvisible.

Modifications of such base plates are known, e.g., from U.S. Pat. No.5,464,960 to Deborah K. Hall as laser calibration device. The lasercalibration device for calibrating surgical lasers is formed bysuperimposition of thin-films of alternating colours. After ablation bya laser beam, the resulting spherical cavity appears as a pattern ofnested circles whose concentricity and spacing reflect the alignment andintensity of the laser beam. These patterns can be visually orinstrumentally analyzed to determine the proper setting of the laser. Amonolayer or multi-layer thin film is used to determine not only theablative power of a laser beam, but also the variation of the ablativepower over the full breadth of the beam by observing the area impingedby the beam between successive laser pulses.

The determined number of shots necessary to ablate the foil and thuscausing a colour change observed by a user may vary depending on theusers subjective perception.

U.S. Pat. No. 7,211,078 relates to a device for monitoring the energyand/or position of a pulsed and scanned laser beam, wherein the pulsedlaser beam is intermittently directed at a sensor. The measuring oflaser energy and in particular the monitoring of laser energy isaccomplished by using optical photodiodes, pyroelectric orthermoelectric sensors. In particular, the laser energy is monitoredduring operation by measuring a divided part of the laser beam.Alternatively, the entire undivided beam can be deflected onto a sensor.

An aspect of the invention is to improve laser energy measurement andmonitoring. In particular, it is an object of the invention to improvethe laser energy measurement and monitoring via sensors. A furtheraspect of the invention is to provide a more objective measurementutilizing a laser calibration tool in order to improve the measurementaccuracy.

SUMMARY

The above objects are achieved by the features of the claims. Aspects ofthe invention are directed to the determination, calibration andmonitoring of a laser beam in view of its energy, energy distribution,position and shape.

A first aspect of the invention is directed to an apparatus and acorresponding method for determining an energy of an excimer laser bythe use of a tool. The tool comprises an area which is ablated by anexcimer laser. The ablation pattern is at least one multi spot ablationpattern, i.e., the ablation is formed by a plurality of laser pulseshaving different target positions on the tool, wherein the size of onelaser pulse is smaller than the ablation pattern. In addition, the toolmay also comprise single and/or double spot ablation pattern. Theplurality of laser pulses of the multi spot ablation pattern may overlapat least partially with one another. The ablation area of the multi spotablation pattern comprises a specific ablation area on the tool, whichmay have the same size as the ablation area or a smaller size. The sizeof the specific ablation area on the tool is analyzed and the energy ofthe excimer laser is determined based on the size of the specificablation area. This analysis is conducted using an image comprising atleast said specific ablation area.

The tool comprises at least two layers having different opticalcharacteristics, e.g., different reflective, transmissive, absorption,colour, colour saturation, lightness characteristics. The two layers maybe formed of a base plate having a planar upper surface on which a foilis located. A laser beam ablates first the foil.

An image capturing means for obtaining the image/the images to beanalyzed may be one of a camera, colour camera, video camera, colourvideo camera. Said analysis for determining the size of the specificablation area may based on optical differences of the layers of thetool. Said analysis may be based on the optical characteristics of onespecific layer of the tool.

The apparatus for determining an energy of an excimer laser may beincorporated in a laser treatment apparatus. It can be used inintervals, for example before a treatment of a patient's eye or once aday.

A further aspect of the invention relates to an apparatus for laserenergy calibration and/or monitoring comprising at least one detectionmeans for detecting a laser beam. Further, the apparatus comprises anevaluation means for evaluating the laser beam energy based on the dataoutput of the detection means. The detection means may be any devicesuitable to determine the laser beam characteristic. It may comprise atleast one optical element, which is located in the laser beam pathduring normal operation, e.g., during a surgical treatment.

This optical element may be any means located in the laser beam path fortransmitting and/or forming and/or focusing and/or reflecting the laserbeam, e.g., a lens or a mirror. The optical element comprises materialproviding at least one of an photoelectric, thermoelectric andpyroelectric effect. The optical element shall be suitable to determinethe laser beam characteristics. The optical element comprises such amaterial to an extent that the optical characteristics of the opticalelement, i.e. reflective and/or transmissive characteristics, aresubstantially not deteriorated. In particular, the material is locatedin such a quantity and location that the laser beam characteristics,e.g., energy and shape are substantially not changed. The material maybe connected via electrical conductors such as conductive wires toprovide an output signal to any analyzing means in response to forexample a pyroelectric effect.

The optical element can be used for continuously monitoring laser energyof a part of the laser beam or the whole laser beam. An erroneousfunction of the laser system either in position or energy may thereforebe detected during the treatment of a patient's eye.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative, non-limiting embodiments of the present invention will bedescribed by way of example with reference to the accompanying drawings,in which the same reference number is used to designate the same orsimilar components in different figures, and in which:

FIGS. 1 a, 1 b are schematic illustrations of exemplary tools ablatedwith different laser energy;

FIG. 2 is a schematic illustration of an apparatus for determining anenergy of an excimer laser;

FIGS. 3 a, 3 b, 3 c are exemplary illustrations of an image processinginput (FIG. 3 a) an intermediate step (FIG. 3 b) and an image processingoutput (FIG. 3 c);

FIG. 4 a is a schematic illustration of an ablation tool comprising twoablations;

FIG. 4 b is a schematic illustration of an ablation tool comprising anfaulty ablation;

FIG. 5 is a diagram illustrating the size of an ablation area of asingle shot ablation pattern under different conditions;

FIG. 6 is a schematic illustration of an apparatus for laser energycalibration and/or monitoring;

FIG. 7 a is a schematic illustration of a mask moving transverse to anaxis of a laser beam;

FIG. 7 b is a diagram showing the detected energy during movement of aslit mask transverse to an axis of a laser beam;

FIGS. 8 a, 8 b are illustrations of measurement zones of a softspot/hard spot laser beam;

FIG. 9 is a diagram showing the theoretical energy in correspondencewith FIGS. 8 a, 8 b for different spot shapes;

FIG. 10 a illustrates a soft spot laser beam with an edge defect;

FIG. 10 b is a diagram showing the detected energy in correspondencewith FIG. 10 a.

DETAILED DESCRIPTION

The upper part of FIG. 1 a shows a cross-section of a tool 10 having afirst layer 12 and a second layer 14. The first layer 12 was ablatedwith a predetermined multi spot ablation pattern having exemplarily acone like shape. In the case of FIG. 1 a the laser energy applied didnot form a breakthrough such that the second layer is not visible asillustrated in the lower part of FIG. 1 a showing a top view of the tool10. The top view of the tool 10 shows the ablation area 20 correspondingto the outer circumference of the multi spot ablation pattern asillustrated by the dashed lines.

It is noted that the predetermined multi spot ablation pattern may havevarious shapes like v-notch, cylindrical, lying cylindrical, a line withgradually increasing/decreasing laser energy, refraction like or anycombination thereof. All utilized ablation patterns have a predeterminednumber of laser pulses. Hence, presuming that the number of laser shotsas well as the ablation pattern is predetermined, the depth ofpenetration of the laser into the tool 10 varies depending on the laserenergy.

In FIG. 1 b the same predetermined multi spot ablation pattern was usedfor ablating the tool as for the tool shown in FIG. 1 a. Thus the samenumber of laser shots was placed on the predetermined positions on thetool. Due to a higher energy of the laser beam the sum of the energy ofall laser pulses created a greater amount of ablation. As a result acone like shaped ablation pattern was formed in the tool 10, said conehaving a greater depth of penetration. The total laser energy appliedwas sufficient to completely ablate the first layer and to form abreakthrough such that the second layer 14 is visible from the top viewof the tool 10. The area wherein the second layer 14 is visible iscalled the specific ablation area 22. The specific ablation area 22 canbe as large as the ablation area 20 or smaller. Due to the fact that thedepth of penetration of the laser into the tool 10 is increasing withincreasing laser energy, the size of the specific ablation area 22 alsoincreases with increasing laser energy. Therefore, the size of thespecific ablation area 22 is a measure for the laser energy.

The first layer of the tool 10 has a predetermined thickness and can beablated with a predetermined number of laser pulses. The tool 10 mayalso be formed of more than two layers. Each of the layers may havedifferent optical characteristics like different reflectivecharacteristics and/or colours and/or colour saturations and/orlightness. In particular, abutting layers may have such differentcharacteristics.

FIG. 2 illustrates an apparatus for determining an energy of an excimerlaser according to a first aspect of the invention comprising a camera30 as an image capturing means and an analyzing means 32 for analyzingthe output of the image capturing means. The camera 30 is one of a photocamera and a video camera taking black-and-white or colourpictures/films. Depending on the type of camera the camera 30 capturesat least one image or a plurality of images at least comprising thespecific ablation area(s) on the tool 10. There may also be more thanone image capturing means, particularly in case of having more than oneablation pattern on the tool 10 to be analyzed.

The analyzing means 32 processes the image data output from camera 30.The analyzing means 32 can utilize an image analysis algorithm toanalyze differences in at least one of lightness and/or colour and/orcolour saturation in the image. In this regard it is noted that the termlightness is used as having the same meaning as the term brightness. Inparticular, the analyzing means 32 may alter the lightness and/or colourand/or colour saturation value of image pixels to another predeterminedlightness and/or colour and/or colour saturation value. An exampletherefore is that a tool comprises a second layer of red material, whichis visible so that an image comprises a certain range of red pixels,e.g., having different colour saturation values which are altered tohave one predetermined colour saturation value. Thus, a kind of mappingis performed, wherein every output value has an input value with acertain range in lightness and/or colour and/or colour saturation. This“mapping” can also have other output values, like “relevant”-“notrelevant”, or “specific ablation area”-“ablation area”-“not relevant”etc.

FIG. 3 a shows an exemplary image data provided by the camera 30. Theimage comprises at least the specific ablation area 22. In the exampleas shown in FIG. 3 a the image comprises almost the whole ablation area20. FIG. 3 a illustrates transition zones 23 from the specific ablationarea 22 to the ablation area 20 and from the ablation area 20 to thefirst layer 12 of the tool 10. Preferably, only a part of the image,i.e. an analyzed ablation area 21, is analyzed. Therefore, asillustrated in FIG. 3 b, the respective part of the image to be analyzedis cut out by software or the like. The analyzed ablation area 21comprises at least the specific ablation area 22. Also, the wholeablation area 20 may be analyzed. FIG. 3 c shows an exemplary imageoutput data after a processing step of the analyzing means 32. In orderto clearly differentiate the ablation area 20 or the analyzed ablationarea 21 from the specific ablation area 22 the pixels of the imageprovided by the camera 30 can be analyzed in view of their gray scalevalue in terms of lightness. Further, similar to the above explained“mapping” example, the lightness of pixels is changed, wherein a pixelhaving a lightness value greater than a predetermined lightness value,i.e. brighter in appearance, is changed to a white pixel and a pixelhaving a lightness value smaller than the predetermined lightness value,i.e. darker in appearance, is changed to a grey/dark pixel having apredetermined grey scale value/lightness. As apparent from FIG. 3 c, thespecific ablation area 22 can then clearly be differentiated from theanalyzed ablation area 21.

Referring back to FIG. 2, the analyzing means 32 can then determine theenergy of the laser pulses applied for ablating the tool 10. Inparticular, the analyzing means 32 determines the laser energy based onthe size of the specific ablation area 22. Data correlating a size of areference specific ablation area with a reference laser beam energy maybe stored in the analyzing means. This reference specific ablation areais compared with the actual size of the specific ablation area 22. Fromthis comparison the actual laser energy of the laser beam which hasformed the ablation as captured by said camera 30 is evaluated. In afirst processing step it may only be determined whether the actual laserenergy is within a certain range, i.e., whether the size of the specificablation area is not too small and not to great. If this test ispositive any further processing may be omitted. Alternatively, the laserenergy may be evaluated in detail. The analyzing means may provide anoutput for adjusting the energy of a laser source based on thedifference of the actual size of the specific ablation area 22 and thesize of the reference specific ablation area.

For determining the size of the specific ablation area 22 by theanalyzing means 32 the respective part of the image comprising at leastthe specific ablation area 22 may be cut out, i.e., only a part of theimage may be analyzed in order to make the processing more efficient.FIGS. 3 b, 3 c illustrate a circular cut-out, however, various cut-outsare possible, like a cut-out covering the whole ablation area 20 or aquadrate cut-out. Such a cut-out may be accomplished after capturing ofthe image as well as before, i.e., by a respective configuration of thecamera 30 in relation to the specific ablation area 22 and/or theablation area 20 or by selecting the relevant data of the image taken bythe camera. Also, the whole image provided by the camera 30 may beanalyzed. The size of the specific ablation area 22 may be determined inpercent in relation to a reference area, the reference area being 100%.Preferably, the reference area is one of the ablation area 20 or theanalyzed ablation area 21.

One possibility to distinguish the ablation areas, i.e., to determinethe size of the ablation area 20 or the size of the analyzed ablationarea 21 and the specific ablation area 22 is to count the number ofpixels falling within a predetermined range in lightness and/or colourand/or colour saturation. Knowing the range of the pixels in lightnessand/or colour and/or colour saturation corresponding to the specificablation area 22 its size can be determined. This range in lightnessand/or colour and/or colour saturation may be stored in the analyzingmeans 32 or obtained via a measurement, e.g., in the middle of anablation area 20. In the latter case it is preferably assured that infact the reference measurement is taken on a place where the first layer12 is completely ablated. This may be accomplished by the analyzingmeans by conducting a validity check. The total number of counted pixelsrepresents a certain area of the image, e.g., the analyzed ablation area21. Thus, the percental size of the specific ablation area 22 can bedetermined relative to the analyzed ablation area 21. Also the number ofcounted pixel relating to the specific ablation area can be correlateddirectly to the energy of the laser. Due to the fact that the ablationpattern(s) have a predetermined, i.e. known, number of shots also themean energy of each laser shot can be determined.

As illustrated in FIG. 4 a also more than one ablation may be formed inthe tool 10 and analyzed according to the invention. The single spotablation area 24 is formed by more laser pulses aimed at the sameposition on the tool 10. This single spot ablation area 24 may be formedduring the formation of the multi spot ablation pattern, exemplarilyillustrated as having a cone like shape. A predetermined number of laserpulses may be directed away from the multi spot ablation pattern to formthe single spot ablation area 24, e.g., in certain intervals. This isadvantageous since the function and accuracy of the laser scanningsystem, i.e. the correct beam deflection, can be checked. Also, sincethe single spot ablation is formed by laser pulses aimed at the sameposition on the tool 10, the laser spot diameter can bedetermined/verified. This, however, presumes that the laser scannerworks correctly, i.e., within a certain accuracy. The two ablation areas20 and 24 may be formed by a different number of laser pulses. Theresults from the single spot ablation can be used to check theapplicability of the multi spot ablation pattern, i.e., in case thecharacteristics of the ablation area 24 do not correspond to a storedreference, which is preferably an ablation area 24 made without movementof the laser scanning system, it may be concluded that also the multispot ablation pattern is incorrect. A failure may be caused, e.g., by adefective laser scanner system, wrong focus, ground motion, vibrationetc.

FIG. 4 b illustrates two ablation patterns like FIG. 4 a, however,single spot ablation area 26 is not correctly formed. One possibilityfor such an ablation pattern is a scanner defect. In this case also themulti spot ablation pattern may show certain deviations (not shown)particularly in the circumference of ablation area 20 or specificablation area 22. As explained above in view of the multi spot ablationarea also the single spot ablation area can be analyzed, e.g., the pixelfalling within a predetermined range in lightness and/or colour and/orcolour saturation corresponding to the single spot ablation area may becounted to determine the size of the ablation area. Alternatively to thesingle spot ablation area, also a double spot ablation area or anablation area with more than two ablation target positions on the tool10 may be employed for determining the characteristics of the laser beamand/or the scanner.

It is noted that in the upper part of FIG. 4 b the single spot ablationarea 26 is illustrated as planar, however, with a laser scanner defector a vibration during the formation of the single spot ablation area 26it may occur that the ablation depth in the peripheral zone is less thenthe central zone.

In FIG. 5 the ablation area for a single spot ablation is shown underdifferent conditions. The ablation area is given in arbitrary units(a.u.). As can be taken from the first four bars (starting from left),there may be a certain range under which the laser is expected to workcorrectly. The fifth bar relates to an exemplary scanner defect. Theablation area significantly increases, however, this may vary dependingon the extent of the scanner defect. The sixth bar illustrates theablation area with a defocus of 3 mm. This means that the point of focusis 3 mm in depth away from the surface to be ablated.

A further aspect of the invention, illustrated in a schematic drawing inFIG. 6, relates to an apparatus for laser energy calibration and/ormonitoring 60. This apparatus 60 comprises at least one detection means,which can detect a laser pulse. The detection means can determine theenergy of a laser pulse and comprises at least one optical element whichis located in the laser beam path. For the sake of completeness, FIG. 6also shows a laser source 50 and a target object 54, like a calibrationtool 10 or a patient's eye to be treated.

The detection means can be realized as an optical element havingreflective and/or transmissive characteristics, i.e. as an integral partof the optical element and/or as a layer on or within the opticalelement. In particular, the optical element may be a mirror 62, e.g. ascanner mirror for deflecting the laser beam during a treatment, and/ora lens 64, 66. The optical element having the detection capability maybe advantageously provided close to the laser source 50 and/or close tothe target 54, i.e., as the last optical element in the beam path beforethe target.

In an aspect, an optical element comprises both optical material,contributing to the optical characteristics, and measurement material,providing a measurement signal. The measurement material provides athermoelectrical and/or pyroelectrical effect and can be electricallyconnected, e.g., via a grid of electrical conductors formed on and/orwithin the optical element. The measurement material, which may notcontribute to the optical characteristic of the optical element isprovided to such an extent and in such a location/distribution over theoptical element to substantially not deteriorate or only to a certainextent the optical characteristics. It is preferred that the measurementmaterial and/or the respective connecting elements are notvisible/detectable in the image plane of the laser pulse.

Further, the apparatus 60 may comprise a comparison means for comparingan actual measurement of the detection means with a previous measurementof the detection means for monitoring the laser beam quality. Instead ofa previous measurement or in addition a measurement by using astandardized light source can be used. The standardized light source mayalso be used for checking and/or calibrating the detection means.

The apparatus 60 may also comprise a mask 68 located in front of thedetection means for selectively blocking at least a part of the laserbeam from the detection means. The mask 68 may be a slit mask, which islaterally moved transverse to the axis of the laser beam. According toan aspect the slit mask is moved at least from one edge of the laserbeam to the opposite edge. The moving of a slit mask may be accomplishedwith help of a stepper motor. FIG. 7 a shows an exemplary mask, whichinitially shadows the complete laser beam and moves gradually away orstepwise in the direction of the arrow, i.e. to the right hand side inthe Figure. In FIG. 7 b the energy distribution is illustrated for eightdifferent positions of a slit mask moved in steps of 0.25 mm. As can beseen from the diagram, a 2 mm hard spot was used and 8 measurements havebeen taken. The measurements show that the increase of the circle shapedlaser spot does not increase in a linear manner, but has a s-shape. Thisis due to the fact that in the first and the last measurements only arelatively little energy change is measured. This measurement data canbe compared to reference values and thus both the total energy of thelaser beam as well as the energy distribution can be measured. In thisway also a misalignment of the laser can be detected.

The mask 68 may also be an iris diaphragm with an adjustable openingdiameter. A laser spot energy distribution can then be determined fromthe center of the beam to the peripheral zone or vice versa. Asillustrated in FIG. 8, the iris diaphragm may have a certain number ofopening positions to detect the laser energy in the respective aperture.FIG. 8 a illustrates a soft spot laser beam and FIG. 8 b a hard spotlaser beam. The respective theoretical energy distribution is shown inFIG. 9, the x-axis relating to the opening diameter of the irisdiaphragm and the y-axis relating to the relative energy in arbitraryunits (a.u.) detected by the detection means. An energy measurement isaccomplished every 0.25 mm from 0 mm to 2 mm. The left part of each barshows the energy of a 2 mm hard spot and the right part of a 2 mm softspot. As can be taken from the measurement values the soft spot has adecreasing energy in the peripheral zone in comparison to the hard spot.This becomes apparent particularly from the last three bars.

The mask 68 may also comprise an aperture having a cake piece like cutout (not illustrated), which is gradually or stepwise rotated about anaxis of rotation. The energy can be detected similar to the aboveexplained examples by taking measurements at different angular positionsof the mask. Also a combination of more mask types may be applied tomeasure different energy distributions of the laser beam across the areaof the laser beam.

With the mask 68 it is possible to measure the beam quality, e.g., beamshape and energy distribution. For each mask position the specificenergy of the laser pulse is measured and can be compared with aprevious measurement or a reference measurement. For processing themeasurement data of the detection means, the apparatus 60 may comprise ahomogeneity check means, comparing the mask location/opening dependentenergy output of the detection means with a stored energy value forevaluating the beam homogeneity.

In FIG. 10 a a soft spot laser beam with an edge defect is illustrated.FIG. 10 b shows the corresponding energy distribution of both atheoretical energy target value and the measured energy value. The edgedefect causes a difference only in the last three opening diameters,starting the measurement with a small iris diaphragm opening diameter,i.e., in the peripheral zone of the laser beam.

It is noted that the above described apparatus for determining an energyof an excimer laser utilizing a tool 10 and the apparatus for laserenergy calibration and/or monitoring 60 may be separately or togetherincorporated into a laser treatment system. In the latter case thedetermined energy and/or laser beam characteristics may be compared orat least one output may serve as a reference.

While certain embodiments have been chosen to illustrate the inventionit will be understood by those skilled in the art that changes andmodifications can be made therein without departing from the scope ofthe invention as defined in the appended claims.

1. An apparatus for determining the energy of a laser, comprising: atool including a base layer and at least one additional layer disposedimmediately adjacent the base layer, wherein the base layer and the atleast one additional layer are each characterized by a material that isablatable by a laser beam, further wherein at least a portion of the atleast one additional layer provides an ablation area to be ablated by amulti-spot ablation pattern from a laser and at least a portion of thebase layer provides a specific ablation area to be ablated by themulti-spot ablation pattern that will be equal to or less than theablation area, further wherein the specific ablation area will providean indicia of the energy of the laser.
 2. The apparatus of claim 1,further comprising: an image capture component disposed to capture animage of the ablation area and the specific ablation area; and ananalyzer component disposed to receive image data from the image capturecomponent and use at least the received image data to determine thelaser energy.
 3. The apparatus of claim 1, wherein the at least oneadditional layer has a predetermined thickness that can beablated-through with a predetermined number of known laser pulses. 4.The apparatus of claim 1, wherein the base layer and the at least oneadditional layer are characterized by different optical characteristicsincluding at least one of reflective characteristics, colours, coloursaturation, and lightness.
 5. The apparatus of claim 2, wherein theanalyzer component includes stored data correlating a size of areference specific ablation area with a reference laser beam energy. 6.The apparatus of claim 1, wherein a different portion of the at leastone additional layer provides a second ablation area to be ablated byone of a single-spot and a double-spot ablation pattern from the laserand a different portion of the base layer provides a second specificablation area to be ablated by the one of a single-spot and adouble-spot ablation pattern from the laser.
 7. The apparatus of claim1, further comprising a therapeutic laser treatment apparatus coupledthereto.
 8. A method for determining the energy of a laser, comprising:capturing at least one image of at least a specific ablation area on atool, wherein the specific ablation area is equal to or smaller than anablation area on the tool and, which is contained within acircumferential boundary of the ablation area; and analyzing the atleast one image, wherein the size of the specific ablation area is anindicia of the energy of the laser.
 9. The method of claim 8, whereinthe analyzing step further comprises analyzing a difference in at leastone of lightness, colour, and colour saturation in the image of the atleast a specific ablation area.
 10. The method of claim 8, wherein theanalyzing step further comprises determining a percentage of thespecific ablation area in relation to a reference area, the referencearea being 100%.
 11. The method of claim 8, wherein the analyzing stepfurther comprises counting pixels falling within a predetermined rangein lightness and/or colour and/or colour saturation, corresponding tothe specific ablation area.
 12. The method of claim 8, wherein theanalyzing step further comprises correlating a size of a referencespecific ablation area with a reference laser beam energy anddetermining the energy of the laser beam based on the size of thespecific ablation area.
 13. The method of claim 8, wherein the analyzingstep further comprises counting the number of pixels falling within apredetermined range in lightness and/or colour and/or colour saturationcorresponding to the specific ablation area.
 14. The method of claim 8,wherein the analyzing step further comprises evaluating a laser spotdiameter based on a second ablation area formed by one of a single spotablation pattern and a double spot ablation pattern on the tool.
 15. Anapparatus for laser energy calibration and/or monitoring, comprising: alaser beam detection component; and a laser beam evaluation componentthat utilizes an output from the laser beam detection component, whereinthe detection component includes at least one optical element disposedto intercept at least a portion of the laser beam, further wherein theoptical element comprises one of a material and a component thatprovides one of a thermoelectrical effect and a pyroelectrical effect.16. The apparatus of claim 15, wherein the optical element is one ofoptically reflective and transmissive.
 17. The apparatus of claim 15,wherein the optical element includes a grid of electrical conductorsformed on and/or in the thermoelectrical and/or pyroelectrical materialor component.
 18. The apparatus of claim 15, further comprising acomparison means for comparing an actual measurement of the detectioncomponent with a previous measurement of the detection component formonitoring the laser beam.
 19. The apparatus of claim 15, furthercomprising a mask disposed in front of the detection component forselectively blocking at least a part of the laser beam from thedetection component.
 20. The apparatus of claim 15, further comprising atherapeutic laser treatment apparatus coupled thereto.